Fluid conduits, such as those utilized to transport crude oil to a tanker, can be cleaned by the use of a pig forced through the conduit by pressured oil. While the pig can be easily forced through a simple fluid swivel, difficulties can be experienced in forcing the pig through a multi-chamber type of fluid swivel. A fluid swivel of this type, such as is shown in U.S. Pat. No. 3,082,440 by Rhedin, includes one or more annular chambers formed between the stationary and rotatable parts of the swivel. It is possible for a pig entering the chamber to move in an endless circle about the chamber and never reach the outlet. It is also possible for the pig to become stuck at the outlet of the chamber, or elsewhere in the chamber, while pressured oil merely flows around the pig. It would be desirable to provide a device that assured movement of the pig through an annular chamber of a fluid swivel into the outlet. It would also be desirable if such an apparatus did not interfere with disassembly of the fluid swivel.